Method for shaping electric wire end and mold for shaping electric wire end

ABSTRACT

To provide a method for shaping an electric wire end and a mold for shaping electric wire end, capable of shaping a distal end with a rectangular shape in sectional view by smoothly pressing conductors of plural electric wires without causing a reduction in strength. 
     In a shaping method of an electric wire end, in which conductors  23  of electric wires stacked mutually are compressed from the stack direction and a distal end  31  with a rectangular shape in sectional view is shaped, by a lower metallic mold  12  and an upper metallic mold  13  provided with shaping grooves  14, 15  having corner portions  14   b,    15   b  for shaping angular portions  31   b  of the distal end  31,  the conductors  23  of the electric wires stacked are compressed from the stack direction and the distal end  31  with the rectangular shape in sectional view in which each of the angular portions  31   b  is shaped by the corner portions  14   b,    15   b  of the lower metallic mold  12  and the upper metallic mold  13  and corner portions  11   a  formed at a boundary between the lower metallic mold  12  and the upper metallic mold  13  is shaped.

TECHNICAL FIELD

The present invention relates to a method for shaping an electric wireend and a mold for shaping electric wire end, in which conductors ofplural electric wires are shaped into a distal end with a rectangularcross section.

BACKGROUND ART

For example, in an ultrasonic bonding method for bonding a conductor ofan electric wire to a terminal by ultrasonic vibration while applyingpressure by a pressurization and vibration horn, the conductor of theelectric wire is shaped into a rectangular shape in sectional view (forexample, see PTL 1 to 5).

In the case of shaping a conductor of an electric wire into arectangular shape in sectional view, as shown in FIG. 8, a conductor 4of an electric wire 3 is arranged in a recessed groove portion 2 formedin a lower mold 1 and in this state, the conductor 4 of the inside ofthe groove portion 2 is pressed by an upper mold 5. Consequently, theconductor 4 of the electric wire 3 is pressurized by the lower mold 1and the upper mold 5 and is shaped in a predetermined rectangular shapein sectional view.

CITATION LIST Patent Literature

[PTL 1] JP-A-4-248283

[PTL 2] JP-A-2000-149755

[PTL 3] JP-A-2004-95293

[PTL 4] JP-A-2006-172927

[PTL 5] JP-A-2009-21176

SUMMARY OF INVENTION Technical Problem

Incidentally, for two electric wires 3 bonded to a terminal, theconductors 4 of each of the electric wires 3 are stacked and pressed andshaped into a rectangular shape in sectional view as described above.For example, when conductors 4 of two electric wires 3 with a radius of1 mm are pressed from a stack direction as shown in FIG. 9( a) and aconnecting terminal portion 6 with a square shape having a width of 2 mmand a height of 2 mm in sectional view is shaped as shown in FIG. 9( b),a dimension of a compression direction is compressed from 4 mm to 2 mm(one-half) and its compressibility ratio becomes 50%. Also, whenconductors 4 of two electric wires 3 with a radius of 1 mm are pressedfrom a stack direction as shown in FIG. 10( a) and a connecting terminalportion 6 with an oblong shape having a width of 2 mm and a height of 1mm in sectional view is shaped as shown in FIG. 10( b), a dimension of acompression direction is compressed from 4 mm to 1 mm (one-fourth) andits compressibility ratio becomes 75%.

When the compressibility ratio is high, there is possibility in that thecenter of the shaped conductor 4 crushes excessively and a high load isimposed on the center and the conductor 4 may suffer damage and cause areduction in strength.

The present invention has been implemented in view of the circumstancesand possibility, and it is an object of the present invention to providea method for shaping an electric wire end and a mold for shaping anelectric wire end, capable of shaping a distal end with a rectangularshape in sectional view by smoothly pressing conductors of pluralelectric wires without causing a reduction in strength.

Solution to Problem

To achieve the object, according to a first aspect of the presentinvention, there is provided a method for shaping an electric wire endin which conductors of electric wires stacked mutually are compressedfrom a stack direction such that a distal end with a rectangular shapein sectional view is shaped, the method comprising compressing theconductors of the electric wires stacked from the stack direction by apair of molds provided with shaping grooves having corner portions forshaping angular portions of the distal end; wherein the angular portionsof the distal end with the rectangular shape in the sectional view isshaped by the corner portions of the molds and corner portions to beformed at a boundary between the molds.

In the first aspect of the present invention, the distal end with therectangular shape in sectional view can be shaped by pressing the pluralconductors while extremely reducing a compressibility ratio. Hence, acompressive force applied to the conductors can be equalized and damageto the conductors is minimized and a reduction in strength can beprevented.

Also, to achieve the object, according to a second aspect of the presentinvention, there is provided a mold for shaping electric wire end, amold for shaping an electric wire end in which conductors of electricwires stacked mutually are compressed from the stack direction and adistal end with a rectangular shape in sectional view is shaped, themold comprising a pair of molds provided with shaping grooves havingcorner portions for shaping angular portions of the distal end; whereincorner portions are formed by edges of the shaping grooves by mutuallybutting the respective molds such that the shaping grooves are aligned.

In the second aspect of the present invention, the distal end with therectangular shape in sectional view can be shaped by pressing the pluralconductors while extremely reducing a compressibility ratio. Hence, acompressive force applied to the conductors can be equalized and damageto the conductors is minimized and a reduction in strength can beprevented.

Advantageous Effects of Invention

According to the present invention, the method for shaping the electricwire end and the mold for shaping electric wire end, capable of shapingthe distal end with the rectangular shape in sectional view by smoothlypressing the conductors of the plural electric wires without causing thereduction in strength can be provided.

The present invention has been described above briefly. Further, detailsof the present invention will become more apparent by reading through amode for carrying out the present invention described below withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a mold for shaping electric wire end accordingto an embodiment of the present invention.

FIG. 2 is a perspective view of an electric wire end targeted forshaping.

FIG. 3 is a front view showing a state of shaping conductors of electricwires by the mold for shaping electric wire end.

FIG. 4 is a front view showing a method of connection of a distal endshaped by pressing the conductors of the electric wires.

FIG. 5 is a front view of a mold for shaping electric wire end accordingto another embodiment of the present invention.

FIG. 6 is a front view showing a state of shaping conductors of electricwires by the mold for shaping the electric wire end.

FIG. 7 is a front view showing a method of connection between a terminaland a distal end shaped by pressing conductors of electric wires.

FIG. 8 is a perspective view showing a conventional example of a shapingmethod of a conductor.

FIGS. 9( a) and 9(b) are views describing the case of shaping conductorsof two electric wires by a conventional shaping method, in particular,FIG. 9( a) is a front view before shaping, and FIG. 9( b) is a frontview of a distal end shaped.

FIGS. 10( a) and 10(b) are views describing the case of shapingconductors of two electric wires by a conventional shaping method, inparticular, FIG. 10( a) is a front view before shaping, and FIG. 10( b)is a front view of a distal end shaped.

DESCRIPTION OF EMBODIMENTS

An example of an embodiment according to the present invention willhereinafter be described with reference to the drawings.

FIG. 1 is a front view of a mold for shaping electric wire end accordingto an embodiment of the present invention, and FIG. 2 is a perspectiveview of an electric wire end targeted for shaping, and FIG. 3 is a frontview showing a state of shaping conductors of electric wires by the moldfor shaping electric wire end, and FIG. 4 is a front view showing amethod of connection of a distal end shaped by pressing the conductorsof the electric wires.

As shown in FIG. 1, a mold 11 for shaping an electric wire end includesa lower metallic mold (mold) 12 and an upper metallic mold (mold) 13.

As shown in FIG. 2, an electric wire 21 whose end is shaped by the mold11 for shaping the electric wire end has a conductor 23 in which pluralstrands 22 are twisted, and this conductor 23 is covered with an outercoat 24. The conductor 23 is formed of a metal material such as aluminumor aluminum alloy. Also, the outer coat 24 is formed of a syntheticresin material such as polypropylene (PP) resin.

As shown in FIG. 3, the mold 11 for shaping electric wire end is a moldfor shaping a distal end 31 with a square shape in sectional view (arectangular shape in sectional view) by mutually stacking the conductors23 of the two electric wires 21 and compressing the conductors 23 fromthe stack direction.

Shaping grooves 14, 15 are respectively formed in the lower metallicmold 12 and the upper metallic mold 13 constructing the mold 11 forshaping electric wire end. These shaping grooves 14, 15 have flatsurface portions 14 a, 15 a for forming surfaces 31 a of the distal end31, and corner portions 14 b, 15 b for shaping angular portions 31 b ofthe distal end 31.

When a radius of the conductor 23 of the electric wire 21 is set at 1 mmherein, length dimensions of the flat surface portions 14 a, 15 a areset at 2 mm and also both angles of the corner portions 14 b, 15 b areset at 90°.

In the case of forming the distal end 31 by integrating the conductors23 of the two electric wires 21 by the mold 11 for shaping electric wireend, the conductors 23 of the electric wires 21 exposed by removing theouter coats 24 in the ends are arranged between the lower metallic mold12 and the upper metallic mold 13 in a state of mutually stacking theconductors 23 (see FIG. 1).

In this state, the conductors 23 of the electric wires 21 are compressedfrom the stack direction by the lower metallic mold 12 and the uppermetallic mold 13.

Then, the conductors 23 of the electric wires 21 are pressed inside theshaping grooves 14, 15 of the lower metallic mold 12 and the uppermetallic mold 13, and the distal end 31 is shaped.

In this distal end 31, right-angled angular portions 31 b are formed inopposed positions by the corner portions 14 b, 15 b of the shapinggrooves 14, 15 and also right-angled angular portions 31 b are formed inopposed positions by corner portions 11 a formed at a boundary betweenthe lower metallic mold 12 and the upper metallic mold 13. Then, thesurfaces 31 a are formed between these angular portions 31 b. That is,the distal end 31 is shaped in a square shape in sectional view, havingthe four angular portions 31 b.

In the distal end 31 formed thus, a length of each side becomes 2 mm insectional view when a radius of the conductor 23 is set at 1 mm, so thata length of a diagonal line becomes about 2.83 mm.

Therefore, when the conductors 23 of the two electric wires 21 arepressed by the mold 11 for shaping electric wire end, a dimension of theconductors 23 in the stack direction changes from 4 mm to 2.83 mm and iscompressed to about 70.75% with respect to the original dimension. Thatis, a compressibility ratio by this mold 11 for shaping electric wireend becomes about 29.25%.

According to the embodiment thus, the distal end 31 with the squareshape in sectional view which is the rectangular shape in sectional viewcan be shaped by pressing the two conductors 23 while extremely reducingthe compressibility ratio. Hence, a compressive force applied to theconductors 23 can be equalized and damage to the conductors 23 isminimized and a reduction in strength can be prevented.

Then, in the case of bonding the distal end 31 shaped as described aboveby an ultrasonic bonding method, the distal end 31 is rotated 45° andthe surface 31 a is arranged on an anvil 41 as shown in FIG. 4. In thisstate, while pressurizing an ultrasonic horn 42 positioned in the sideopposite to the anvil 41 with the distal end 31 sandwiched between theanvil 41 and the ultrasonic horn 42, ultrasonic vibration is produced bythis ultrasonic horn 42.

Consequently, the ends of the two electric wires 21 are bonded at thedistal end 31 by the ultrasonic vibration.

Next, another embodiment will be described.

In addition, explanation is omitted by assigning the same numerals tothe same structural portions as those of the embodiment described above.

FIG. 5 is a front view of a mold for shaping electric wire end accordingto another embodiment of the present invention, and FIG. 6 is a frontview showing a state of shaping conductors of electric wires by the moldfor shaping electric wire end.

As shown in FIG. 5, in a mold 11A for shaping electric wire endaccording to another embodiment, a butted position of edges of a shapinggroove 14 of a lower metallic mold 12 and a shaping groove 15 of anupper metallic mold 13 is shifted. Consequently, respective lengths offlat surface portions 14 a are varied in the shaping groove 14 and alsorespective lengths of flat surface portions 15 a are varied in theshaping groove 15. Concretely, when a radius of a conductor 23 is set at1 mm, in the shaping groove 14, a length of one flat surface portion 14a is set at 1 mm and a length of the other flat surface portion 14 a isset at 2 mm. Similarly, in the shaping groove 15, a length of one flatsurface portion 15 a is set at 1 mm and a length of the other flatsurface portion 15 a is set at 2 mm.

As shown in FIG. 6, in the case of forming a distal end 31 byintegrating the conductors 23 of two electric wires 21 by the mold 11Afor shaping electric wire end, the conductors 23 of the electric wires21 exposed by removing outer coats 24 in the ends are arranged betweenthe lower metallic mold 12 and the upper metallic mold 13 in a state ofmutually stacking the conductors 23 (see FIG. 5).

In this state, the conductors 23 of the electric wires 21 are compressedfrom the stack direction by the lower metallic mold 12 and the uppermetallic mold 13.

Then, the conductors 23 of the electric wires 21 are pressed inside theshaping grooves 14, 15 of the lower metallic mold 12 and the uppermetallic mold 13, and the distal end 31 is shaped.

In this distal end 31, right-angled angular portions 31 b are formed inopposed positions by corner portions 14 b, 15 b of the shaping grooves14, 15 and also right-angled angular portions 31 b are formed in opposedpositions by corner portions 11 a formed at a boundary between the lowermetallic mold 12 and the upper metallic mold 13. Then, surfaces 31 a areformed between these angular portions 31 b. That is, the distal end 31is shaped in an oblong shape in sectional view (a rectangular shape insectional view), having the four angular portions 31 b.

In the distal end 31 shaped thus, a length of a long side becomes 2 mmand a length of a short side becomes 1 mm in sectional view when aradius of the conductor 23 is set at 1 mm, so that a length of adiagonal line becomes about 2.236 mm.

Therefore, when the conductors 23 of the two electric wires 21 arepressed by the mold 11A for shaping the electric wire end, a dimensionof the conductors 23 in the stack direction changes from 4 mm to 2.236mm and is compressed to about 55.9% with respect to the originaldimension. That is, a compressibility ratio by this mold 11A for shapingelectric wire end becomes about 44.1%.

Also in the case of another embodiment described above thus, the distalend 31 with the oblong shape in sectional view which is the rectangularshape in sectional view can be shaped by pressing the two conductors 23while extremely reducing the compressibility ratio. Hence, a compressiveforce applied to the conductors 23 can be equalized and damage to theconductors 23 is minimized and a reduction in strength can be prevented.

Then, in the case of bonding the distal end 31 shaped as described aboveby an ultrasonic bonding method, the distal end 31 is rotated properlyand the surface 31 a is arranged on an anvil 41 as described withreference to FIG. 4. In this state, while pressurizing an ultrasonichorn 42 from the side opposite to the anvil 41, ultrasonic vibration isproduced by this ultrasonic horn 42.

The case of shaping the conductors 23 of the two electric wires 21 bypress and shaping the distal end 31 and then bonding the distal end 31by the ultrasonic bonding method and connecting the conductors 23 hasbeen described up to here. Further, the case of shaping the conductors23 of the two electric wires 21 by press and shaping the distal end 31and then bonding the distal end 31 and a terminal by a terminalultrasonic bonding method and connecting the conductors 23 and alsoconnecting the conductors 23 to the terminal will hereinafter bedescribed. FIG. 7 is a front view showing a method of connection betweena terminal and a distal end shaped by pressing conductors of electricwires. In addition, a process of shaping the conductors 23 of the twoelectric wires 21 by press and shaping the distal end 31 is describedwith reference to FIGS. 1 and 3 or FIGS. 5 and 6, so that theexplanation is omitted.

In the case of bonding a terminal 51 and the distal end 31 describedwith reference to FIGS. 1 and 3 by an ultrasonic bonding method, thedistal end 31 is rotated 45° and the surface 31 a is placed on an uppersurface of the terminal 51 as shown in FIG. 7. Further, the terminal 51on which the distal end 31 is placed is arranged on an anvil 41. In thisstate, while pressurizing an ultrasonic horn 42 positioned in the sideopposite to the anvil 41 with the distal end 31 and the terminal 51sandwiched between the anvil 41 and the ultrasonic horn 42, ultrasonicvibration is produced by this ultrasonic horn 42.

Consequently, by the ultrasonic vibration, the ends of the two electricwires 21 are bonded at the distal end 31 and also the distal end 31 isbonded to the terminal 51.

In addition, the present invention is not limited to the embodimentsdescribed above, and modifications, improvements, etc. can be madeproperly. Moreover, as long as the present invention can be achieved,the number of components, materials, shapes, dimensions, arrangementplaces, etc. of each of the components in the embodiments describedabove are arbitrary and are not limited.

This application is based upon and claims the benefit of priority ofJapanese Patent Application No. 2010-188558 filed on Aug. 25, 2010, thecontents of which are incorporated herein by reference.

INDUSTRIAL APPLICABILITY

According to the present invention, the shaping method of the electricwire end and the mold for shaping electric wire end, capable of shapingthe distal end with the rectangular shape in sectional view by smoothlypressing the conductors of the plural electric wires without causing thereduction in strength can be provided.

REFERENCE SIGN LIST

-   11,11A MOLD FOR SHAPING ELECTRIC WIRE END-   11 a CORNER PORTION-   12 LOWER METALLIC MOLD (MOLD)-   13 UPPER METALLIC MOLD (MOLD)-   14,15 SHAPING GROOVE-   14 b, 15 b CORNER PORTION-   21 ELECTRIC WIRE-   23 CONDUCTOR-   31 DISTAL END-   31 b ANGULAR PORTION

1. A method for shaping an electric wire end in which conductors ofelectric wires stacked mutually are compressed from a stack directionsuch that a distal end with a rectangular shape in sectional view isshaped, the method comprising: compressing the conductors of theelectric wires stacked from the stack direction by a pair of moldsprovided with shaping grooves having corner portions for shaping angularportions of the distal end; wherein the angular portions of the distalend with the rectangular shape in the sectional view is shaped by thecorner portions of the molds and corner portions to be formed at aboundary between the molds.
 2. A mold for shaping an electric wire endin which conductors of electric wires stacked mutually are compressedfrom the stack direction and a distal end with a rectangular shape insectional view is shaped, the mold comprising: a pair of molds providedwith shaping grooves having corner portions for shaping angular portionsof the distal end; wherein corner portions are formed by edges of theshaping grooves by mutually butting the respective molds such that theshaping grooves are aligned.